I was going to replace the bearings and syncros on the gearbox of my '60 PV.
Found that the layshaft and spindle are begining to show signs of pitting.
As these items are in short supply, I am at a crossroad.
I disassembled an early M40 gearbox and it seems that the layshaft and spindle are the same length and diameter as an M4. Even the mainshaft seems to be the same length and uses the same front and rear roller bearing.

The two overall differences that I found between the two gearboxes were;
The M40 spinle will not extend through the back side of the M4 casing (this shouldn't be a problem);

The M40 input shaft will have to be machined to reduce it's length to be the same as the M4 shaft length.

Obviously all the M40 gears will have to be used as they are not interchangeable with M4 gears.

So the question is, has anyone tried putting all M40 guts into a M4 case?

Thanks
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'86 745T, '72 144E, '70 145S, '68 122S Estate, '60 544